I've never understood the fascination with tube amps for playback. I've heard many of them, and I simply never hear anything odd or unusual, or most of all, preferential. In my experience, with the exception of hot cheap garbage, the vast majority of amps (tube and solid state) are sonically transparent, unless over driven.
I know someone who's determined to buy one, and told me that he only reads positive testimonials, and I can't dispute that. I just wonder why the fascination...